They switched to a float type in the later camheads. I'm assuming they continued this with the wetheads.

Morning Lone_RT_rider

The RTW does use a float type fuel level sensor, there was a level sensor update/supersede on the earlier RTW bikes with a new design float type sensor for the 17 bikes (what's different I don't know).

The upside of the float type sensor system is it is more conventional so less long term issues, the downside is it is very difficult to get a float on an arm to accurately track fuel level in a convoluted & irregular shaped fuel tank. In fact on the BMW (pre 17) 800GS bikes the fuel gauge only reads from 1/2 tank to empty due to the float system's inability to track the fuel level in the upper part of the tank.

Understandable, but just a random thought ... why would it not be possible to track capacity by weight. Given a known volume and weight of gasoline and weight of fuel tank one would think it would be a simple task. I must be missing something ...
Or why not a "fuel consumed" indicator by monitoring injector flow or calculating a value since the air / fuel ratio and mileage traveled is known?

Afternoon chrisolson


Understandable, but just a random thought ... why would it not be possible to track capacity by weight. Given a known volume and weight of gasoline and weight of fuel tank one would think it would be a simple task. I must be missing something ..-- It would be possible given enough money, talent, & mounting space. The tank isn't a nice cylinder so it would need a number of attachment mounts, it would have to use a load cell as ALL mounting points then average those inputs. Due to jarring of the bike, fuel line attachments, mud buildup, Tupperware attachments, working temperatures etc, to be accurate, it would need a way to do an empty tank calibration very often (probably at every start up). This brings on the question of HOW to do an empty tank load cell calibration without emptying the tank?

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Or why not a "fuel consumed" indicator by monitoring injector flow or calculating a value since the air / fuel ratio and mileage traveled is known?--This would work (sort of anyhow). It already uses that info for approximate fuel range. Again some problems to overcome as it is probably pretty close to knowing exact fuel used when in closed loop but what about fuel used during engine warm-ups before the o2 sensors come on-line (this is just a past history guess without exact o2 input). The downside is it is basically a best-guess at how much fuel remains in the tank but it doesn't really know exactly how much so if it gets out of kilter a bit (fuel leakage, lots of warm-up idling, lots of hard accelerations out of o2 sensor range, alcohol content in the fuel, etc can leave a dry tank with fuel still showing in the tank. Or a showing out-of-fuel on the gauge with 50 miles remaining in the tank.

The only fuel gauge that always works without issue is what I have on a couple of my dirt bikes (a see through fuel tank so you can see the fuel level remaining) but even that has issues as you can't easily see it while riding the bike).

Most larger jet aircraft measure fuel quantity by weight. They also compensate for the specific gravity of the fuel, which varies according to its temperature. Measuring quantity in an odd shape is done by using multiple fuel quantity probes. The fuel probes consist of two cylinders, one inside the other, the fuel level between these cylinders change the capacitance of the probe, from which fuel quantity is derived. That's the simple part. Connecting the probes with wire and repeatedly calibrating the system to compensate for the capacitance of the wiring is gainful employment for some.

The funky BMW fuel strip is not all that bad of an idea. Too bad manufacturing outsourced it to the wrong cheap ass vendor.

Hey Lone Rider - I ride at least every week or two this time of year so the sitting period wasn't a factor.

My fuel strip replacement history is about once a year or every 25000 miles - give or take. Dealer is only 10 miles away and repair is FREE. . ALWAYS set my trip odometer and compare this to both computer miles-remaining-in-tank and gallons remaining in tank at fillup AND the computer is AWESOME/UNCANNY accurate. I routinely run util computer says 15 miles to go (when I know gas is available), about half a gallon in tank, about 300 miles range! I LOVE my Fuelstrip/Computer (as long as I get free replacement). Best (except at failure) and most ACCURATE fuel-remaining system I have ever had.

Too bad yours is the exception and not the rule. BMW needs to bite the bullet and do a recall on all bikes with a retrofit for the fuel strip system. Problem solved.

Can you replace the 05-09RT fuel pump and level sensor with the 10-13RT fuel pump and level float? It sounds like the 10-13RT do not have the fuel level problem the earlier model does.

Afternoon sdbc

Can you?-- probably,,,, will it work?-- probably not without some sort of complicated electronic conversion matching box to allow the 05-09 electronic dash gauge electronics to read the float output in a form it can use & understand.